An apparatus for obtaining 3-D surface contour image data of a tooth has a double telecentric optical system disposed to form an image of the surface of the tooth onto an image detector array. A focus adjustment mechanism is actuable to adjust the position of either or both the double telecentric optical ' system and the image detector array along an optical axis to each of a sequence of focus positions. A control logic processor is in control signal communication with the focus adjustment mechanism to adjust focus position, and is in image data communication with the image detector array for receiving image data obtained by the image detector array and with a memory for storing the received image data corresponding to each of the sequence of focus positions. The control logic processor is further responsive to stored instructions for computing 3-D surface contour image data from the image data.
